<x-charset iso-8859-1>Chere Isabelle and all!
It seems I am forced to respond to you, whether I like it or not, by
Angella's kind comments.
1. I have no experience with Fmoc-Lys(Me2)-OH. But try whatever you can to
get it into solution so you can do the coupling. Coupling should proceed
normally. The dimethylamino should not interfere with anything.
2. The product will be as stable as anything. The dimethylamino is basic,
so will present at the HCl, TfaOH, whatever salt, if last in contact with
acid.
3. I don't think methylating with methyl iodide or similar is a good idea.
In principle, methylation should not stop at the dimethyl stage, as Angela
seems to have found. .
4. On a simple molecule the simplest approach to dimethylamino is
catalytic hydrogenation in the presence of formaldehyde, which guarantees a
dimethyl, and not mono or tri. Mono is easier to methylate than the amino
group. I am not aware of this having been done on a resine-bound peptide.
But, catalytic hydrogenation HAS been used successfully in solid phase
synthesis with benzyloxycarbonyl-amino acids. So it may well work.
I'd have to dig out pertinent references if you want them.
Good luck. NLB.
At 01:25 PM 5/15/01 -0400, you wrote:
>Hi All,
> >
> > I have to synthesize a peptide containing a dimethyl-lysine. Since
there are
> >other Lys in the sequence, I know that I can use Fmoc-Lys(Ddiv) or some
> > other protected Lys derivatives that allow selective deprotection. Is
> > there anyone who has some information about how I can add a dimethyl or a
> > trimethyl on the deprotected lysine? Is the final product relatively
> > stable? Should I use some particular conditions for the HPLC
purification ?
> >
> > I will REALLY appreciate any informations or reference that you have...
> >
> > I'm using a 433 peptide synthesizer from applied biosystem with the Fmoc
> > technology. Activation with HBTU/HOBT in DMFand DIEA.
> >
> > I bought a Fmoc-Lys(Me)2-OH from Bachem but it seems that it's not soluble
> > in these conditions...
> >
> > Thanks! Isabelle
>
>
>
>
>Isabelle Kelly MSc.
>Service Protéomique de l'Est du Québec,
>CHUQ Pavillon CHUL,
>2705, Boul.Laurier,
>Ste-Foy, Québec,
>G1V 4G2
>
>Tel. 418-656-4141 ext. 7088
>Fax. 418-654-2159
>http://www.crchul.ulaval.ca/crchul/en/serv/Default.htm
>
>
N. Leo Benoiton Professor Emeritus of Biochemistry
Faculty of Medicine
University of Ottawa, Tel: 613 562 5800 ext. 8216
451 Smyth Road, Fax: 613 562 5440
Ottawa, Ontario, Canada K1H 8M5 eMail: benoiton@uottawa.ca
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